To site-admins running openacs sites with the backup script from openacs: newer versions of Gnu tar (starting at least with tar 1.27) don't allow the combination of the "c" (create) and "s" (preserve-order) flag. This combination leads to failure during backup. If you are using the backup script coming with or derived from the OpenACS distribution, please remove the "s" from the tar command in the backup script (see [1]).
Background: the "s" flag was introduced for small machine that would not otherwise be able to hold all the names of the files to be processed in memory, which is for scenarios where OpenACS is used no issue. The man page of tar says that this option is probably never needed on modern computer systems.
The patch will be included in OpenACS 5.9.
[1] http://cvs.openacs.org/browse/OpenACS/openacs-4/etc/backup.sh?r1=1.13&r2=1.13.12.1
